1. Field of the Invention
The present invention generally relates to a method and an apparatus for storing data, for example, electronic mail data. More specifically, the present invention is directed to such a storing method and such an apparatus, capable of storing data while effectively utilizing a small storage capacity of a memory.
2. Description of the Related Art
Portable terminals used in portable telephone systems are specifically required to be made compact and in low cost. As a result, generally speaking, a storage capacity of a memory employed in such a portable terminal is greatly smaller than that of a personal computer.
In the case that a portable terminal is used as an electronic mail terminal, the below-mentioned difficulties may occur because of such a small memory capacity. That is, when such a portable terminal is tried to receive electronic mail data transferred from a personal computer, for instance, this portable terminal directly receive such electronic mail data via a network, e.g., the Internet, a memory full condition will immediately occur. Under this memory full state, the user of this electronic mail terminal cannot receive subsequent electronic mails, or is forcibly required to delete the received electronic mails from this memory.
To solve the above-explained memory full problem caused by a small memory capacity, several application software and communication services have been provided. For example, in the electronic mail application software, the indication of the header is selected. In the mail application software, the electronic mails which have received and have passed for longer than a preselected time period are automatically deleted. In the personal computer communication service, the user can freely select whether or not the electronic mail header data is transferred.
In the above-explained electronic mail application software capable of selecting the indication of the header, the unnecessary sort of headers can be selected by the user so as to restrict the header indication. Precisely speaking, the unnecessary data are not displayed on the electronic mail terminal, for example, the route information and the message ID, which are contained in the header and cannot directly give influences to the content of the main document. Also, such data are not required to be displayed due to limitations in the display screen, and/or due to use conditions. In a personal computer, generally speaking, a user can display an electronic mail after the user once decides not to display this electronic mail, while this electronic mail is saved in a memory unit such as a hard disk unit of this personal computer. However, since a portable terminal is not equipped with such a hard disk type memory, this solution is not properly applied to such a portable terminal.
In the mail application software capable of automatically deleting such electronic mails which have been saved for more than a preselected time period, since the saving time period of the electronic mail in the personal computer is restricted, a total number of saved electronic mails can be automatically reduced. In this case, since this application software judges that the older electronic mails are unnecessary mails, this application software cannot correctly judge whether or not the older electronic mails are actually unnecessary mails. Under such a circumstance, this application software cannot be directly applied to such portable terminals.
In the above-explained personal computer communication service, the headers of the electronic mails are not transferred. This software can save the data transfer time. However, it is useless to secure a memory region for storing unnecessary header data. Moreover, if such an unnecessary memory region is secured, then a total memory capacity would be reduced, so that the actually stored data amount, namely number/data amounts of electronic mails, would be decreased. Also, there are some electronic mail data which can be hardly judged as unnecessary mail data. Therefore, this communication service cannot be directly applied to such a portable terminal.
Japanese Laid Open Patent Application(JP-A-Heisei 1-212046) describes the following mail buffer management technique. That is, while the lengths of the messages which can be stored in the storage apparatus every terminal are set, an entry of a new message which exceeds this set value is rejected by the mail buffer management system. When the unused memory capacity of the storage apparatus is smaller than, or equal to a predetermined value, a new message may be stored in the storage apparatus in this mail buffer management system.
However, in this mail buffer management system, the following mail storing operation cannot be done. That is, the new mail message is partially selected in accordance with the present unused memory capacity of the storage apparatus, and then this selected mail message portion is stored. Also, since the older mail messages which have been saved for more than a preselected time period are recognized as the unnecessary mail messages, this mail buffer management system cannot correctly judge the actually required mail message.
Also, Japanese Laid Open Patent Application(JP-A-Heisei 4-353951) discloses the electronic mail deleting system used in the electronic mail system.
This conventional electronic mail deleting system is arranged by the delete subject mail condition input means 4 for inputting the deletion condition of the mail to be deleted, the delete subject mail condition judging means 5 for producing the retrieve condition from the condition entered from the delete subject mail condition input means 4, the delete subject mail retrieving means 6 for retrieving the delete subject mail 3 from the mail box file 2 based upon the retrieve condition, the delete subject mail confirming means 7 for confirming the deletion of the mail 3 to be deleted via the prepared input/output means 9, and also the delete subject mail deleting means 8 for deleting the mail 3 which is confirmed to be deleted by the delete subject mail confirming means 7 from the mail box file 2.
This conventional mail deleting system may solve such a problem that the saved mails are deleted one by one, resulting in a lower efficiency. That is, after the plural mails have been saved in the storage apparatus and the mail reception time has passed preselected time, or predetermined expiration date, these plural mails are deleted one by one, which causes the low efficiency in the mail deletion.
However, this mail deleting system cannot achieve the above-explained purpose that when the mail data is stored into the memory, the memory capacity is effectively used.
Also, Japanese Laid Open Patent Application(JP-A-Heisei 5-199261) describes the following electronic mail system.
This conventional electronic mail system is arranged by the mail box maintenance condition instructing unit 1 for setting the deletion condition of the electronic mail, the mail box maintenance unit 20 for deleting the electronic mail from the mail box file 6 in accordance with the deletion condition, the automatic operation condition instructing unit 3 for setting the time condition used to delete the electronic mail, and the automatic operating unit 4 for automatically initiating the mail box maintenance unit 2 in accordance with the time condition.
This conventional electronic mail system can automatically delete the unnecessary electronic mail from the mail box file 6 by combining the mail box maintenance unit 2 and the automatic operating unit 4. As a result, even in such an electronic mail system that there is no job for continuously monitoring the mail box, the unnecessary electronic mails can be regularly and effectively deleted irrespective of the user's condition and the system manager's will, and further the 24-hour operable system.
However, this electronic mail system cannot achieve the above-explained purpose that when the mail data is stored into the memory, the memory capacity is effectively used.
Also, Japanese Laid Open Patent Application (JP-A-Heisei 5-252200) discloses the below-mentioned electronic mail managing apparatus.
In this electronic mail managing system, the management information table 2 stores thereinto at least one of the management information, e.g., constant time, a total number of mails stored in the mail box 11, a memory capacity, and a memory remaining capacity of the mail box 11. The judging means 1 judges as to whether or not the mail stored in the mail box 11 is made coincident with at least one of the above-explained management information stored in the management information table 2. The saved mail list file 7b saves at least one of first several lines contained in the mail sender, the mail sending data, and the main mail document. The save processing means 6 saves the respective mails contained in the mail box 11 into the mail save file 7a when the judging means 1 judges that the mail is coincident with the management information. And, this save processing means 6 saves the mail sender into the saved mail list file 7b.
In accordance with this electronic mail managing apparatus, before a large number of electronic mails are stored in the mail box, the stored mails can be properly deleted/saved for the sake of easy mail reference occurred in near future.
However, this mail deleting system cannot achieve the above-explained purpose that when the mail data is stored into the memory, the memory capacity is effectively used.
Furthermore, Japanese Laid Open Patent Application(JP-A-Heisei 6-97962) discloses the following electronic mail system.
In this conventional electronic mail system, when the empty capacity of the mail box is smaller than, or equal to the reference capacity, such an electronic mail having a low importance degree is prohibited to be saved into the mail box, depending upon the importance degree data contained in the additional information of the electronic mail. As a result, when the electronic mail having the high importance degree is arrived, this electronic mail can be stored into the mail box with a top priority. Also, the electronic mails having the high importance degrees can be practically stored into the mail box with priority degrees by employing the following method. That is, the mail box is previously subdivided into a plurality of areas. These areas are ordered based the stored orders. All of the electronic mails are stored into the areas in the vicinity of at least heads of the storage orders irrespective of the importance degrees thereof. On the other hand, such electronic mails having lower importance degrees are prohibited to be stored into at least the area having the last storage order.
However, this electronic mail system cannot partially select the electronic mail in accordance with the empty capacity, and cannot store only the selected mail portion. Also, this electronic mail system judges that the mail messages which have saved for more than a preselected time period and also the old mail messages are equal to the unnecessary mail message, so that this conventional mail system cannot correctly judge the actually required mail messages.
The present invention has been made to solve the above-described drawbacks, and therefore, has an object to provide a data storing apparatus and a data storing method, capable of using a memory having a small memory capacity.